In the various world university ranking schemes, the "Overall" is a sum of the weighted indicator scores. As the indicators are of a different nature from each other, "Overall" conceals important differences. Factor analysis of the data from three prominent ranking schemes reveals that there are two factors in each of the ranking systems. For Academic Rankings of World University, the two factors are both academic in nature with a time element and are "negatively" correlated. For the QS World University Ranking (QSWUR) and Times Higher Education World University Rankings (THEWUR), there are two factors each, one for academic excellence and one for managerial excellence. The two factors in QSWUR have a low negative correlation, but the two factors in THEWUR are not correlated. These findings do not support the assumption that the indicators are mutually supporting and additive as conceptualised by the ranking providers. To avoid misinterpretation of the "Overall," it is suggested that world university ranking needs be re-conceptualised to have a higher-order "institutional" excellence, comprising two lower-order measures based on "academic" excellence and "managerial" excellence. Possible future development is discussed.